2000tc 10:1 to 9:1 conversion

[Sam363]

Hi All,

First time posting.

I have a 73 2000tc engine currently in bits, and whilst it's apart I am contemplating the 9:1 compression ratio conversion.

Not wanting to seem silly but:

To achieve this would simply swapping to flat topped SC pistons achieve this; or would I also need to change the con rods for a shorter stroke?

Pictures of my mashed up engine for interest.

Thanks for your help!

Sam

 

[Vern Klukas]

The 9:1 pistons are all the same. And the 2000 only had the single con rod part number.

So just the pistons will fix you up.

Yours
Vern

 

[sdibbers]

Or you can do what I and @johnsimister did, which is to use 2200 9:1 pistons and conrods. That way you can drop the compression ratio while keeping (or even adding) a bit of torque. One word of warning is the 2200 conrods are needed too.

 

[redrover]

It's dead straightforward, and a very worthwhile conversion to make the engine more tolerant of modern fuel. I did it years ago. Pull the rods out, swap the pistons for 9:1 types, put it all back together again.

I have a set of 9:1 pistons (standard bore) going spare if you're looking for some. I'm fairly sure they have new Cords rings on them too. I'll check.
I'd always hone the bores with a glaze busting tool before fitting replacement pistons and rings. They are cheap to pick up - pop one in a handheld drill and add plenty of oil.

Worth noting none of the 2000 pistons were flat topped (that was the change for 2200). All 2000 pistons were all the dished heron types. The principle difference was the volume of the dished section - lower volume meant higher compression. See below. 10:1 on the right has a larger radius on the dish, whereas the 9:1 has a tighter radius. The crown wall is also slightly thicker on the 10:1, which all goes to create more volume:


There were other detail differences over the years to skirt design and bore lubrication slots, but they're all interchangeable as sets.

Michael

 

[Sam363]

Thanks all for your replies!

At the moment I'm leaning towards just changing the pistons ( keeping it 2000) as I don't intend on really using the full capabilities of the engine.
(I have a pinto powered cortina for that!)

@sdibbers do / did you find it a noticeable torque gain even when driving more 'miss Daisy' like?

I was hoping to claw some of the loss back with timing /afr, but if it is a really noticeable loss I may rethink my approach.

@redrover thanks for your comment, that's really useful, detailed knowledge. Also thanks for the offer of pistons! Unfortunately, my block has already had some work done prior to this latest round, and I've been advised I'll need some +60's.

Thanks once again!

 

[johnsimister]

The torque improvement with the 2200 pistons is instantly noticeable, even with the drop in compression ratio. The engine becomes considerably smoother, too, possibly because the 2200 pistons are lighter (shallow dish and they don't come to the top of the bores) and the changed combustion chamber shape allows a more progressive burning of the fuel. If you're getting the engine rebored anyway, it makes sense to bore it more (to 90.5mm) and fit 2200 pistons (same 9:1 compression ratio for 2200 SC and 2200 TC). You can use the original conrods if you have the small ends machined to make them slightly narrower, although I used 2200 ones in mine having acquired a donor (and very tired) 2200 TC engine.

Whatever you decide to do, you'll also need to think about getting a distributor to match the new state of tune because your original advance curve will be wrong.

 

[redrover]

@redrover thanks for your comment, that's really useful, detailed knowledge. Also thanks for the offer of pistons! Unfortunately, my block has already had some work done prior to this latest round, and I've been advised I'll need some +60's.

No worries.

Good luck in your search.
+0.060"s are vanishingly rare to the extent that several very knowledgable P6 folk don't even believe they exist.
They do, and I know they do, because I'm putting a set in my rebuild (NOS Hepolite). But mine were a fluke find on eBay.

You might find JP in Australia stock them (theirs are remanufactured... and you MUST read the instructions on clearances, which are not standard). But outside of that, you'll probably find yourself searching for a long time. If you can find JPs to fit, you'll almost certainly need to machine the block to their larger tolerances. So with that in mind, the advice to move up to 2200 is probably sensible, as the parts are at least more available. Or source a replacement block and swap them over.

Good luck with it